(Rhythm combo starts up out of vision and Sgt. Duckie sings. This is all part of the Policevision Pan-European song contest, of course. Superimposed caption on screen: 'SGT DUCKIE'S SONG.' Duckie performs a showy, happy dance and jauntily twirls his whistle chain.)   Duckie:   I'm a little bit sad and lonely   Now my baby's gone away...   I'm feeling kinda blue   Don't know just what to do   I feel a little sad today. Chorus of PCs:   He's a little bit sad and lonely   Now his baby's gone away   He's feeling kinda blue   He don't know just what to do   He's not feeling so good today. Duckie:   Wheeeen I smile   The sun comes flooding in (dadadadadada)   But wheeeen I'm sad   It goes behind the clouds again. Chorus:   He's a little bit sad and lonely   Now his baby's gone away   He's feeling kinda -      (they stop abruptly and say:) etcetera, etcetera